MEMS elements require a defined environment in order to function properly. This pertains especially to the surrounding pressure. Rotation-rate sensors, in particular, but also other sensors require a low surrounding pressure that remains stable across the service life of the sensor regardless of environmental influences.
According to the related art, a getter material may be used to adjust the pressure in the cavity of a sensor. This is advantageous especially if multiple sensors having different cavity pressures are to be produced on one chip, e.g., a combo element made up of an acceleration and a rotation-rate sensor. In this case, a getter material is introduced into the cavity of the sensor featuring a lower pressure, e.g., the rotation-rate sensor. This is disadvantageous insofar as the activation of the getter takes place thermally during the bonding process. As a result, no separate optimization of the bonding process and the getter activation is possible.
Another possibility consists of using the getter as a stabilizer of the cavity pressure across the service life. For this purpose a getter material is introduced into a cavity, in which case the task of the getter is restricted to the adsorption of gas emissions from the sensor and/or the cap. Here, too, the getter material is thermally activated.
Essential getter materials and methods for their production are discussed in the documents EP1410433, EP1412550 and EP1869696, for example.